Arcane season 2 makes a lot of very big things happen, and some of you may be wondering if all of this is canon to the main League of Legends universe.

Well, yes and no. Riot Games has insisted that Arcane is the main canon, and have said that they are going to change the broader League of Legends universe to fit it, so that people who watched Arcane can play League of Legends and not be confused by different versions of the character running around.

So in that sense, yes, Arcane is canon.

Now, Riot has said they're going to do that, but also… they haven't actually done that yet. To be fair, it's not something you can just do overnight, I'm sure it'll take a while, but for the moment, the reality is that the overwhelming majority of published story that actually exists… contradicts Arcane, almost entirely. And despite having three entire years since season 1 to start making things fit… even the champions of just Piltover and Zaun have not yet had new material published that would make them fit with the story of Arcane.